<VV> Cyl. Temp. Gage

[Dave Thompson]

Try unplugging the thermister wire at the firewall and measuring it to
ground. Then giggle the wire.

Dave Thompson

-----Original Message-----
From: jerry dixon [mailto:dixonja at psci.net] 
Sent: Tuesday, November 18, 2008 12:17 PM
To: Dave Thompson
Subject: Re: <VV> Cyl. Temp. Gage

Thanks for the advice, when I get a warm day I will try to check thermister 
my self.
                          Jerry D
----- Original Message ----- 
From: "Dave Thompson" <dave.thompson at verizon.net>
To: "'jerry dixon'" <dixonja at psci.net>; <virtualvairs at corvair.org>
Sent: Sunday, November 16, 2008 1:30 PM
Subject: RE: <VV> Cyl. Temp. Gage


> >From personal experience....
>
> My CHT gauge failed. I replaced the thermister and all was good. A few
> hundred miles later, the needle started to jump around. After some 
> watching
> I realized that it jumped around when there was movement of the engine, 
> such
> as hitting bumps or a good rev of the engine. I pulled the lower shroud 
> and
> found that the tiny 4-40 nut holding the ring terminal on the thermister 
> had
> come loose. The terminal was bouncing around on the stem with a loose nut.

> I
> couldn't use a nylon lock nut due to the heat and the nylon melting (I
> guessed). So I went to the model airplane store and found a 4-40 crimp 
> nut.
> I'm not sure what the proper name is but there is a tip on the nut that
> resembles a nylon lock nut. The tip has slots cut in it and works the same
> as a nylon lock nut. However it is all metal. I installed it on the
> thermister to hold the wire and I haven't had any problems since for 
> several
> thousand miles. Also check to be sure that the threads are clean and rust
> free. You need a good electrical connection on the wire.
> By the way, a thermister can be tested by measuring with an ohmmeter 
> between
> the large threads and small threads at each end. You should get something
> around 500 ohms at 70 degrees F. As I'm sure you know the gauge is not
> accurate. You just find out what is normal for your car and watch for
> something abnormal before you get alarmed.
>
> Good luck.
> Dave Thompson
> 63 Spyder vert
> Westminster, CA
>
>